Leaders of a newly created Syrian opposition coalition were due Friday in London for talks with British Foreign Secretary William Hague, opposition sources said, dpa reported.
The head of the National Coalition of Syrian Revolutionary and Opposition Forces, Ahmed Moaz al-Khatib, and three members of the alliance were scheduled to meet with Hague.
Britain was expected to urge the alliance to put forward a clear plan for political transition in Syria, the BBC reported.
In return, the British government would consider granting official recognition to the coalition as the legitimate opposition to the regime of President Bashar al-Assad.
Inside Syria, government troops launched an assault on the rebel-held area of al-Rastan, in the central province of Homs, according to opposition activists.
Al-Assad's troops, meanwhile, shelled the restive town of al-Zabadani, on the outskirts of the Syrian capital Damascus, reported the opposition Syrian Observatory for Human Rights.
At least 140 people were killed on Thursday across Syria, including 34 in the suburban areas of Damascus, added the Britain-based organization.